1. Field of the Invention
The present invention relates to an ink jet printer, an object-to-be-printed holding member, and a printing method.
2. Description of the Background Art
In recent years, objects to be printed of an ink jet printer are not only flat media such as paper or films, but also 3-dimensional objects having various shapes. In association with this tendency, a method of holding printed objects (works) having various shapes are also studied. For example, in the related art, a method of performing three-dimensional printing continuously by mounting the work on a rotating unit is known (for example, see JP-A-2011-20112). There is also a known method in which when printing on a rotating body having a plurality of ink droplets landing surfaces as a work, a printing operation is performed while rotating the rotating body (see JP-A-2010-158874).
In recent years, with glowing popularization of handheld terminals such as smart phones, covers for such handheld terminals are now in increasing demand. Accordingly, the inventors of the present application have studied earnestly about how to hold works when printing on 3-dimensional objects like covers for the handheld terminals such as smart phones with an ink jet printer.
When printing on the covers for the handheld terminals, printing not only on surfaces which cover back surfaces of the terminals, but also on side surfaces which intersect the back surfaces is desired. Since the covers for the handheld terminals are products which are required to be excellent in design, printing with great precision is desired. On the other hand, since the prices of these products are low in comparison with those of main bodies of the handheld terminals, printing with lower costs is desired.
In order to realize these desires, the inventors of the present application have studies earnestly firstly about the method of printing on works having a shape such as the covers for the handheld terminals more adequately with the ink jet printer. Consequently, the inventors have found that adequate printing on each of the surfaces of the works is achieved by mounting the works such as the cover of the handheld terminals on shaft members and rotating the shaft members to change the orientation of the works.
The inventors of the present application also have studied about problems occurring newly when printing on the works in this method. Consequently, the inventors have found that when the printing is performed with the configuration described above by using ultraviolet curing ink, there may occur a problem of leakage of stray light from positions where the ultraviolet rays to be irradiated for curing the ink are deviated.
More specifically, in a case where printing on works such as covers for handheld terminals, for example, when changing the orientation of the works by rotating shaft members on which the works are mounted, in order to set surfaces which cover back surfaces of the terminals (main surfaces to be printed) as surfaces to be printed, the rotational position of the shaft members are aligned to predetermined positions so that the main surfaces to be printed oppose an ink jet head. When side surfaces are the surfaces to be printed, the shaft members are rotated so that the side surfaces oppose the ink jet head.
In this case, the position of the surfaces to be printed in the direction of discharge of ink droplets (for example, in the vertical direction) in the case where the main surfaces to be printed are the surfaces to be printed may differ from that in the case where the side surfaces are the surfaces to be printed. When changing the position of the surfaces to be printed, gaps which allow leakage of ultraviolet rays may be created, and hence the problem of stray light may occur.
However, when printing is performed by using the ink jet printer, an operator (user) may perform an operation of the printer in the vicinity of the printer. Therefore, leakage of the ultraviolet rays is not preferable. The leaked ultraviolet rays may cause deterioration of printer components, or resin components in the periphery thereof. Therefore, the amount of the stray light leaked to the position deviated from the work is required to be as small as possible.